pomerof



(No Model.)

B. H. POMEROY. DRILL'AND TAP soALB.

Patented Mar. 3, 1'89L @.Wo CD1-w? A TTURJVE'Y thread and a No.1() torolearanee:

iint're dentes .errent Futon.

eo., on nnoontrs, NEW Yon'ii.

'DRILL AND. T? SCALE.

snnetmon'mon forming pere ef Lettere Patent No. 447,475, dated Meren s, 1891. Application iiledlebruary 6, 1889. Renewed January 27, 189].. Serial No. 379.245.. (N0 model.)

To all whom if nmyeoncel'n.

13e it known that. l, BENNARD ll. IOMEROY, a citizen of the vUnited States, and a resident of the City, county, and State ot' New York, have invented a new and useful Improvement in Drill and 'lap Scales, of which the followingr is a specification. l

'ihe object et' this invention is to facilitate the selection of proper drills for taps.

The invention consists in arranging the size of taps, number of drills for the propersize of thread and learanoedrills, so that they eau be readily selected without the usual annoyance of oalipering'.

Figure ishons my improved scale provided with the proper figures and characters to in'- dieate the size, and Fig. 2 shows a niodiieation as to shape.

A represents a seale provided with my iinprorements made from sheet metal or other suitable material.

Previous-to my invention, in selecting a roper driii tora tap, it was eustoinary to test ie size by ealiperine'or hydrilling a hole in a pie-ee et metal and try the tap to see it the drill was suitable. .lhis required a great loss ot time and ineonvenienee, ueeessitatiner many mistakes'. 'lo avoid this trouble and to facilitate the seleotion,I print or stamp upon suitable material a graduating-scale, whieh shows at a glance the proper-size drills which should be used for the tap selected.

In drilling holes for serews two sizes are frequently required, one forthe thread, eallod the tap-drill, the other, large enough te admit the serew, called the clearance-drill.

Column i3 upon the scale indicates the size ot' the tapsand the number of threads tothe inch. Colunnri. gives the size'of the tapdrill, whieh is smaller than the tap, so that a suitable thread will be out. (.oluinn l) indicates the size it the (clearance-drill, which is 'lartre enougggn to admit of the tree passage of the serew. 'lhus it will be seen thata -'-l tap will require a No. 50' drill t'or the 'i`he holes -lil and E are the size of the drills for taps is provided with numbers to denote the di- 5ol ameter of the drills, as at on.. This can be used instead of the holes E.

A, Instead of shaping the scale as in Fig. 1, l may arrange it as in Fig'. 2, which I show as a modification', the letters and numbers eor- 55 responding to those of Fig. 1. I have notshown a full set of taps and drills, but sullieientto explain my invention. I do notdeem it essentialto have the holes E E. or 1"; but

for convenience to test drills not numbered 6o orin making new ones I combine it with the scale.

Having thus fully described my improvement, what I desire to seeure'by Letters latent of the United States isl. A sealeprovided with the eoluinn ll, designating,` the size of tl1etaps,\in combination with the, column C, designatingr the size of tap-drills', es and for the piu-poses specified.

). A seule provided with the eoluinn l, des- 7o ignating the size of the taps, in combination with the eoluinn l), designating the sizeof tho clearance-drills, as and for the purpose speelllied.

3. A scale provided with the column il, des- 7 ignating the sizeof taps, in combination With the eolumnC, designating the size ot the tapdrills, and column l), designating,r the size of the clearance-drills, as and for thev purpose spoeilied.

-l-. A scale provided with theeolunin il, designatint,r the size of the taps, in combination with the hole l, designating the size ot' the elearanee-drills, and hole E', designating the size of the tap-drills, as and for the purpose 85 speeiiied.

In testimony whereotl Subscribe my name in tho presence of two witnesses.

i3 INNARI) ll. IOMEROY. Witnesses.

li). 'l. THOMAS, Wu. ld. JoHNs'rON. 

